1. Field of the Invention
The present invention relates to simulation systems and, more particularly, to helicopter flight simulators.
2. Description of the Prior Art
Flight simulators attempt to recreate a flying environment so as to efficiently hone the flying skills of a pilot. Of course, the more realistic the flight simulator, the more accurately the skills learned in the simulator can be transferred to an actual aircraft.
Of particular relevance to the present invention are flight simulators that relate to helicopters, although the present invention includes aspects that are applicable to other flight simulators as well. Helicopter simulators are cost effective means for teaching not only routine flight procedures, but also emergency procedures. For instance, one common emergency procedure for landing without power, called autorotation landing, can be learned on a flight simulator.
To achieve realism, most modern flight simulators apply three-dimensional graphics to a video display. Much effort towards realizing true life video images has been expended in the general area of mapping a three-dimensional world onto a two-dimensional video display. One such system that addresses this problem is described in the patent to Sims, et al. (U.S. Pat. No. 4,586,038).
There has also been much work performed in the general area of accurate simulation modeling, and some of the modeling techniques used in flight simulators have been transferred into the domain of entertainment software and arcade games. In particular, one instance of an arcade game having the general concept of a video simulator game that attempts to replicate helicopter flight is the "Air Inferno" game sold by TaitoAmerica Corporation of Wheeling, Ill.
Nonetheless, while the general concepts of helicopter simulation, computer imaging or animation, and arcade game simulation have been developed over the years, currently available flight simulators lack many possible visual cues which could provide the degree of realism expected by the user of a flight simulator. Moreover, there are a number of modeling issues which have not been properly addressed by flight simulators. Lastly, flight simulators that do exist are usually quite expensive, some on the order of tens of millions of dollars. It would thus be desirable to develop a flight simulator/arcade game for beginner training and entertainment that would cost orders of magnitude less than the noted existing simulators.
Discussing visual cues first, one such cue which has been identified but not adequately implemented is aircraft shadowing. That is, as the aircraft flies, a shadow follows the terrain underneath the aircraft. The aircraft shadow is thus one means of providing the pilot with a perceived cue of aircraft altitude. Previous work on an altitude cue based on the use of landing lights and spotlights during night operations was discussed by Fortunato, et al. (U.S. Pat. No. 4,511,337). In the arcade game domain, which usually requires much less expensive computer hardware and more compact computer software, aircraft shadowing has been implemented in such games as "Hydra", an arcade game sold by Atari Games Corporation of Milpitas, Calif. However, these and other like previously implemented systems have employed shadowing on either a flat ground or on a block or step-like terrain, with attendant limitations as to realism and limited value as a cue to aircraft altitude.
Another more recent implementation of aircraft shadowing is found in the "F-15 Strike Eagle" game manufactured by MicroProse Software of Hunt Valley, Md. This game, which uses polygon graphics to simulate 3D images, provides shadows over hills where the aircraft is not necessarily parallel to flat terrain. Nevertheless, the visual cueing of this game departs from reality in that the aircraft shadow is always in front of the aircraft, or, in other words, the simulated or artificial sun always trails behind the aircraft.
Thus, an important visual cue to incorporate in flight simulators would be a terrain following shadow for airborne objects which could be projected on a sloped terrain at an angle determined by an artificial light source or sun. Such a visual cue would enhance the user's perception of altitude, emulating the aircraft shadow that naturally occurs during low altitude flight.
Simulator training would be improved if accurate atmospheric conditions could be reproduced by a flight simulator. Atmospheric conditions caused by particles in the air or the position of the sun in the sky, for example, will mute and distort the environmental colors perceived by a pilot. The change in coloration can be thought of as resulting from a screen or grid of haze being overlaid on the image. Such a visual cue of color change, henceforth termed hazing, would provide a greater degree of realism in simulators, allowing users to test their flying abilities under varying environmental conditions.
Hazing, or simulating non-optimal atmospheric conditions, is used in some present military simulators to simulate flying in fog, or some other form of haze. However, the known military simulators require expensive computer hardware, including high resolution video displays, to reproduce these effects.
Moreover, with infinite resolution on a video display, the simulation of atmospheric conditions such as fog, smoke, smog, dusk, and the like, would be perfect, i.e., fine droplets or granules could be interleaved with the view. Alternatively, the human eye could be deceived into seeing higher video resolutions than actually available by employing higher rates of video frame update. Unfortunately, most present video systems have limited resolution and slow rates of video update. In addition, the choice of colors in video displays is often limited due to constraints on video memory.
Due to the above-mentioned problems, pilots desiring realistic training having visual cues which change colors according to atmospheric conditions have either had to have access to expensive equipment or have had to simply do without. A flight simulator having the capability to approximate atmospheric conditions using many readily available and reasonably priced video display systems would therefore be a great benefit in training pilots.
In addition to the above stated need for improved visual cues in flight simulators, further advances in aircraft modeling need to be made. First, flight training is enhanced by the ability of a simulator to move the camera away from the viewpoint of the pilot since, among other things, many beginners feel more comfortable flying in "third person", i.e., actually seeing the aircraft being flown. Many video games have used so-called third person perspectives of a graphical universe. More recently, video games have been provided with "first person" views of gameplay by the generation of simulated three-dimensional perspectives such as the specialized computer hardware discussed in Hoff (U.S. Pat. No. 4,467,412).
Changes in viewpoints have also been used to change the viewing angle of a playfield by a "camera" to either an overhead view of the entire terrain or to a ground level view where the ground action is occurring. This type of operation was seen in "I, Robot" an arcade game produced by Atari, Inc. The change of viewpoint in "I, Robot" was further enhanced because it was user selectable, i.e. , the user could change the view at any time during the game. Another change in viewpoint function was embodied in the "G-Loc" game sold by Sega Enterprises, Inc., of San Jose, Calif., which simulates air-to-air battles. "G-Loc" changes viewpoints from first person, i.e., the camera is in the cockpit, to third person, i.e., the camera is outside of the aircraft. However, since a player is only backed out of the cockpit into third person if an enemy aircraft is behind the player, the viewpoint change implemented in "G-Loc" is not user selectable.
Others have implemented user selectability but have not addressed improving realism by incorporating a zoom when changing the viewpoint or, if so, have not implemented first-to-third person changes. For instance, another air combat game called "Blue Max", manufactured by Three-Sixty Pacific of Campbell, Calif., allows the player to fly either behind the aircraft or in the cockpit at the press of a button. However, there is no zoom when the viewpoint changes between first and third persons. Lynx, a hand held video game player manufactured by Atari, Inc. of Sunnyvale, Calif., includes a cartridge for "California Games" a skateboarding adventure game In "California Games" the player can change camera angle and camera pitch which, for example, zooms in on a skateboarder at the top of a pipe. Nonetheless, there is no change from first to third person in "California Games".
Thus, although changes in viewpoint and user selectability have been presented in previous arcade games, there is not now either a simulator or a game which provides a user selectable, continuous zoom, between first and third persons. Such a function, including continuous zoom, is desirable to create a flexible, seamless change in viewpoint which, by changing user perspective, increases the educational use of a simulator, or the entertainment value of a game.
Further realism in flight simulators could also be achieved by providing automatic ground avoidance. In the Atari game called "Battlezone", missiles avoided terrain obstructions by performing a "cylinder search", or "conical search", wherein the radius of the search would be reduced with increasing altitude. Once the cylinder search located a height of an object which would cause a collision, the model would move the missile to an altitude which would avoid the interfering object. The "Afterburner" game also available from Sega Enterprises, Inc., provided another form of ground avoidance. However, Afterburner does not include a realistic terrain as the ground is completely flat. The F-15 Strike Eagle game, previously mentioned, provides a degree of vertical ground avoidance at the beginning of the game to prevent a crash, but the type of ground avoidance practiced therein is limited to terrain at sea level altitudes. It would therefore be desirable to provide a flight simulator which avoided terrain of varying altitudes, both horizontally and vertically, and simultaneously simulated the effective aircraft controls to avoid the ground.
One model feature for flight simulators which is specific to helicopters, and has been previously addressed by expensive commercial simulators but not entertainment software or arcade games, is autorotation landings. Autorotation is the flight condition wherein no engine power is supplied to the main rotor of a helicopter. In emergency situations, such as engine failure, the helicopter may be safely landed if the pilot is familiar with the technique. Certainly, simulation of emergency situations is of an extraordinary benefit when compared to having a pilot actually try such a maneuver in flight.
Consequently, a need exists for an improved helicopter flight simulator having the above-identified improvements including visual cues such as terrain following shadows and approximation of varying atmospheric conditions. Further improvements in flight modeling, as mentioned above, are needed, including user selectable zoom, automatic ground avoidance and, in a helicopter simulator, autorotation model features. Perhaps most importantly, it would be desirable to combine one or more of these features in a low cost flight simulator/arcade game for beginner pilots and game players.